In recent times halls have been increasingly constructed of glass or with large glass areas, in which the glass panes are held in glass securing means of a grid lattice construction in the form of an external or internal skeleton. Frequently, such halls are so designed that the glass panes, proceeding from the apex of the roof, are inclined by a specific angle to the respective preceding pane. As in the case of such large glass areas the problem of their cleaning arises, the use of cleaning robots is considered in this area.
When a robot or vehicle moves on glass surfaces, a main problem resides in the selection of suitable kinetics for the drive and direction control of the robot or vehicle. If the construction of the glass area contains members which can serve as guide members for the robot and which permit an application of force, e.g. rail systems, these members are used for the transporting movement. If such constructive members are not present or are unsuitable, the application of force must be effected directly into the glass.
In this case problems arise in that, in order to transport the robot, the drive member, for example in the form of a wheel, must apply a force to the glass which on the one hand is greater than the rolling friction resistance between glass and wheel plus the adhesive and rolling friction resistance of the respective drive train, such as motor, bearing and the like. On the other hand the force applied must be smaller than the adhesive friction resistance between wheel and glass, as otherwise slip would occur and the wheel would "skid". As the magnitudes of the named minimum and maximum forces at low friction coefficients lie very close to one another, extremely sensitive regulation is necessary.
In addition to the transporting movement, controlled steering, i.e. influence on the direction of movement, is always necessary. The steering constructions known from the automobile are unsuitable due to the lack of available space.